code: def simple_model(config):
      model = tf.keras.Sequential(
          [
              tf.keras.layers.InputLayer(input_shape=(1,)),
              tf.keras.layers.Dense(10),
              tf.keras.layers.Dense(1),
          ]
      )
      return model
  
file_path: BigDL/python/orca/test/bigdl/orca/learn/ray/ctx/test_tf2_ray_dataset.py
imports: import pytest
  from unittest import TestCase
  import ray
  from ray.data import Dataset
  import tensorflow
  from bigdl.orca.learn.tf2 import Estimator
  from bigdl.orca import init_orca_context, stop_orca_context
label_desc: Use image node_id 3 for calling a global function with example usage: simple_model(config) and returns: model